PRIMERS, ADHESION PROMOTERS, COATINGS AND SEALANTS FOR RUBBERS and MOST COMBINATIONS OF SUBSTRATES

Rubber
is an elastic hydrocarbon polymer, also called an elastomer
and is a thermoset material. Thermoplastics are materials
with the property becoming
hard and rigid when cured and are moldable when heated. Rubber
softens or fuses when heated and hardens and becomes rigid
again when cooled without undergoing any appreciable chemical
change. Natural rubber comes from a
milky emulsion in the sap of several varieties of plants,
called latex. Rubber can also be produced synthetically through
the polymerisation of a variety of monomers to produce polymers.
Synthetic rubber can be derived using many different chemical
formulae or blended with other chemicals, giving it different
chemical properties, and produced in varying thicknesses,
both of which affect its coefficient of expansion.

Silicone
rubber is vulcanized using peroxide or sulfur and, sometimes,
platinum to cure it. Silicone rubbers, such as caulking compounds,
are composed of one or two part liquids cured with moisture
or platinum or metal. Successful long term bonding of rubber
to itself -- and to other substrates -- requires careful
preparation and matching of the adhesive being used with
the differing coefficients of expansion (COE) and chemistries
of the substrates involved. This COE differential is not
usually an issue in bonding rubber to rubber but may be an
issue when bonding rubber to rigid substrates, depending
on the rubber. BONDiTTM products
are among the few available that can be used to bond rubber
to substrates with differing COE's and chemistries for harsh
environments and long term deployment without debonding.

Our first
recommended product for the vulcanized rubbers is the BONDiTTM B-45.
BONDiTTM A-43 will bond to cured
RTV silicone as a primer. BONDiTTM B-45
will then bond to the A-43.

Our recommendation would change if Aflas or silicone rubber or RTV silicone
is one of the substrates, in which case we recommend priming that substrate
with an adhesion promoter, such as BONDiTTM A-43,
prior to using B-45. If bonding EPDM or neoprene to silicone, we recommend
priming the silicone with A-43, coating C-31 on top of that, and then vulcanizing
the EPDM rubber to silicon rubber.

Your
application may call for other BONDiTTM adhesives
or primers, depending on the resistance to chemicals, moisture
or impact, or elongation required. To see our tables comparing
properties of the various BONDiTTM products
click here.